1. Field
Embodiments of the invention generally relate to the field of semiconductor manufacturing processes, more particularly, to methods for forming a contact metal layer on dielectric substrate.
2. Description of the Related Art
Semiconductor processing involves a number of different chemical and physical processes whereby minute integrated circuits are created on a substrate. Layers of materials which make up the integrated circuit are created by chemical vapor deposition (CVD), physical vapor deposition (PVD), epitaxial growth, and the like. Some of the layers of material are patterned using photoresist masks and wet or dry etching techniques. The substrate utilized to form integrated circuits may be silicon, gallium arsenide, indium phosphide, glass, or other appropriate material.
As feature sizes have become smaller, the cross section dimensions of logic metal contacts and subsequent metal interconnect layers are decreasing rapidly. CVD cobalt may be used as metal deposition technique for application as metal interconnects. Conventionally, a cobalt thin film is grown on dielectric material such as silicon dioxide or low-k dielectric. Use of organometallic precursors negates the need of a barrier layer, which is used in alternate metal CVD processes utilizing halide based chemistry. However, incubation (growth) of the cobalt layer on the dielectric material is poor and results in non-continuous growth. A titanium nitride (TiN) nucleation layer may be formed on the dielectric material prior to CVD deposition of cobalt layer. However, titanium nitride will not deposit on the dielectric material at less than 300° C. The cobalt layer is deposited at a temperature between 100° C. and 250° C. Thus, two processing chambers may be utilized for the depositions of the nucleation layer and the cobalt layer.
Therefore, an improved method of forming a cobalt layer is needed.